1. Related Application
This application is a continuation-in-part of application ser. no. 780,280 filed on Oct. 18, 1991 now U.S. Pat. No. 5,129,594 entitled Avionic Tray and Method of Making Same.
2. Field of the Invention
The present invention relates to avionic racking trays and more particularly to avionic trays and a method of manufacturing such trays in which the electrical connector carried by the tray is accurately positioned for mating contact with the connector carried by the avionic equipment supported on the tray.
3. Description of the Prior Art
Avionic racking trays have been known in the art for a long time. More particularly, in accordance with the usual practice in the aircraft building industry, each piece of electronic equipment used in an aircraft is contained in a separate container which is supported by an individual tray. The trays are, in turn, mounted substantially at their respective front and back ends on cross beams provided in the aircraft. The trays are usually made in standard ATR (aircraft tray racking) widths to accommodate various sizes of instruments. It is customary to mount the electronic instruments, such as radios, inertial navigation systems, radar systems etc., in rectangular boxes, generally painted black. As a result such avionic instruments are sometimes referred to in the trade and in the ensuing description as "black boxes".
The trays are usually mounted above a plate attached to the cross beams, so that the plate and the bottom sections of the trays and the cross beams jointly form an air plenum chamber. Air is usually continuously evacuated from or forced out of the air plenum chamber to cool the components inside of the black boxes. The trays usually have a depressed central portion into which a separate metering plate, having one or more air metering holes, is mounted, surrounded by a gasket.
The usual avionic racking trays include vertical side rails disposed at the lateral edges of a substantially horizontally disposed base plate or bottom of the tray. A back plate is mounted with fasteners (such as bolts and nuts) between the side rails. The back plate has one or more openings or cut-out portions into which one or more female (half) electrical connectors are mounted Such connector halves contain a multitude of female receptacles which receive male electrical connector pins extending outwardly from the male connector half carried by the electronic equipment.
The back plate must be disposed precisely at a right angle relative to the base plate or bottom of the tray in order to enable the male pins of the electronic equipment to engage matching female receptacles in the electric connector half mounted to the back plate. Attaching the back plate to the side rails by ordinary nuts and bolts, however, does not provide sufficient precision for this purpose. As is described in detail in U S. Pat. No. 3,710,476 this problem has been solved in the prior art by providing jig pins in the interior side of the side rails. The back plate is then provided with holes to register with the jig pins to provide a self-aligning assembly, which is fastened together by bolts and nuts, or other like fastener means.
The solution to the back plate alignment problem afforded by the '047 patent requires complex manufacturing operations resulting in an expensive tray. In particular, the formation of the jig pins on the side rails requires the use of accurately controlled punches and dies to half shear the pressed metal which become the jig pins. In addition, this operation requires that the back plate have lateral sides or flanges which adds to the overall weight and cost of the tray.
There are significant advantages to be gained in the art by reducing the complexity of the manufacturing operations and structure necessary to produce a tray in which the back plate is precisely aligned with respect to the tray bottom and side rails. The present invention accomplishes this task while providing a less expensive tray with improved back plate alignment.